1) 3 ц 2/3 + 1/5 = (3 3 + 2) / 3 + 1/5 = (9 + 2) / 3 + 1/5 = 11 / 3 + 1/5 = (11 5 + 1 3) / (3 5) = 55 / 15 + 3 / 15 = 58 / 15

Ответ: 3 ц 13/15

2) 3 ц 2/5 - 1 ц 3/7 = (3 5 + 2) / 5 - (1 7 + 3) / 7 = (15 + 2) / 5 - (7 + 3) / 7 = 17 / 5 - 10 / 7 = (17 7 - 10 5) / (5 * 7) = 119 - 50 / 35 = 69 / 35

Ответ: 1 ц 34/35